The present invention relates to a machine for packing different types of products in a thermoretractable film.
It is well known to pack different types of products such as foodstuffs, printing or stationary articles, or mechanical parts in thermoretractable films welded on their edges.
A machine of this type is essentially composed of:
a roll of film center-folded in two layers PA1 means, such as a pin or the like, to separate the two layers of film and to place the product to be packed, therebetween, PA1 a welding station where the periphery of the two layers of film is welded edge-to-edge about the product; and PA1 a retraction station where the whole assembly is subjected to a heat treatment in order to cause the retraction of the film about the product, thus adopting the shape of said product. PA1 a fixed working table which is perforated and designed to receive the product inside the wrapper to be retracted, PA1 a bell part, pivotally mounted on one of the edges of the working table, and of which two adjacent sides, forming L, are equipped with electric welding elements; and PA1 heating means, operationally coupled to blower means, placed on the other side of the working table. PA1 a roll supplying a supple film center-folded in two layers, for wrapping a product, PA1 means for separating the two layers of film, PA1 means for welding the periphery of said film, PA1 means for retracting the film about the product to be packed, PA1 on the one hand, to slide horizontally along the table so as to sweep the surface of the product to be retracted, after edge-to-edge welding; PA1 and on the other hand, to pivot inside an orthogonal plane with respect to the plane of the table. PA1 the movable structure parallel to the table comprises: PA1 the welding means are composed of a frame, of which two L-forming contiguous sides are equipped with electric heating elements, said frame being tiltable about the longitudinal axis parallel to the table and guiding the end of the tiltable movable structure, whereas the other end of said structure is guided inside a longitudinal slide provided to this effect inside the frame; PA1 the working table is constituted by a metallic grid, adjustable in height with respect to said movable frame; PA1 the movable retraction frame, slidable and tiltable about and along the longitudinal axis parallel to the table, is fast with the welding frame and comprises:
In U.S. Pat. Nos. 4,104,848 and 4,162,604, a machine of the aforesaid type is proposed in which the welding station and the retraction station are regrouped into one station, essentially composed of:
According to this rather cumbersome arrangement, the pivotally mounted bell part being in most cases opaque, the product to be packed is then hidden from the operator throughout the whole welding and retraction operation, this preventing the operator from controlling this operation and from intervening if the need arises. Moreover, when the operator raises the hinged bell part, once the operation is completed, the hot air contained therein rises up to his face, which is unpleasant. Finally, whatever the size of the product to be packed, it is necessary at each operation to heat the entire volume inside the bell, which constitutes a great and unnecessary expense.
It is the object of the present invention to overcome these disadvantages by proposing a machine of the aforesaid type for packing goods in a thermoretractable film, or which is of reasonable dimension, and reasonably cheap to build and to run, and in which the product being packed is always visible throughout the critical phase of retraction, thus permitting the intervention of the operator if the need arises during the said phase, and finally a machine which can be used even by inexperienced people.
The improved machine for wrapping goods in a thermoretractable film, according to the invention, which is of the type comprising:
and in which machine the welding and retraction means are regrouped into one working station on a fixed table. The retraction means are constituted by a movable structure, disposed in parallel to and above the fixed table, said structure being equipped with a source of hot air directed towards the table and being able
In other words, the invention consists in using in the single working station, as retraction means, no longer a hinged bell part, but instead a heating structure, which is likewise pivotally mounted, but which also enables to sweep the whole surface of the product to be packed.
Advantageously, in practice,
a hollow transverse arm, which is open on its face opposite the table, and which is mounted for pivoting about and along a longitudinal axis parallel to the edge of the table, said hollow arm being joined to a fan blowing air onto heating elements provided inside said hollow arm, PA2 and an operating handle placed at the end of the hollow arm opposite that receiving the pivoting pin, permitting the actuating of said arm along and about said pin; PA2 blower means; PA2 two parallel and hollow transverse arms, placed on either sides of the grid table, each arm comprising:
a conduit connecting it with the blower means, PA3 an electric heating element, PA3 a longitudinal slot situated opposite the working grid and designed to direct the hot air blow onto the films to be retracted, welded around the product to be packed, PA3 an operating handle, fixed on the end of the upper arm and designed, after the edge-to-edge welding of the two layers of film, to enable the longitudinal sliding of the movable frame along and about the working table.